The present invention is directed to a novel organometallic luminescent material, and more particularly, to a novel organometallic luminescent material having the capability of emitting pure blue light and high thermal stability, and an organic electroluminescent device (OELD) containing same.
Conventional organometallic luminescent compounds used in organic electroluminescent devices are mostly complexes of divalent or trivalent metals such as zinc and aluminum.
For example, U.S. Pat. No. 5,456,988 describes 8-hydroxyquinoline complexes of zinc, aluminum and magnesium as organic luminescent materials; U.S. Pat. No. 5,837,390 discloses magnesium, zinc and cadmium complexes of 2-(o-hydroxyphenylbenzoxazole); Japanese Patent Laid-Open Publication No. 07-133483 reports luminescent complexes of 2-(o-hydroxyphenylbenzoxazole) with divalent metals such as magnesium and copper; and U.S. Pat. No. 5,529,853, and Japanese Patent Laid-Open Publication Nos. 06-322362, 08-143548 and 10-072580 disclose divalent or trivalent metal complexes of 10-hydroxybenzo[10]quinoline.
The above organometallic luminescent compounds containing a divalent or trivalent metal have relatively loosely-bound ligands and an extended system of conjugation. As a result, they are relatively unstable and emit green or red light but not blue light.
Therefore, there has existed a need to develop an organometallic luminescent material having an improved stability and light emission characteristics such as the capability of emitting pure blue light.
Accordingly, it is a primary object of the present invention to provide a novel organometallic luminescent material having good stability and desired emission characteristics, and an organic luminescent device containing same.
In accordance with the present invention, there is provided an organometallic luminescent complex of formula (I). 
wherein,
M1 is a monovalent or tetravalent metal selected from the group consisting of Li, Na, K, Zr, Si, Ti, Sn, Cs, Fr, Rb, Hf, Pr, Pa, Ge, Pb, Tm and Md;
R is hydrogen or C1-10 alkyl;
B is O, S, Se or Te;
D is O or S; and
n is an integer ranging from 1 to 4.